1. Field of the Invention
This invention relates to a recording liquid, a recording method and a method for forming color images by use thereof. It relates particularly to an ink jet recording method.
2. Related Background Art
Heretofore, various compositions have been reported for inks for use in ink jet printing.
Among them, comprehensive researches and developments from both aspects of composition and physical properties have been made regarding inks especially for printing on paper recording media.
However, some problems are involved in inks of the prior art for ink jet printing. The greatest problem is that the paper which is generally used in offices such as notebooks, reporting paper, copying paper, typewriting paper, letter paper, bond paper, continuous business forms, etc., cannot be used.
When ink jet printing is carried out on the various kinds of paper mentioned above by use of prior art ink, the ink will spread along the fibers of the paper, whereby the dot shape becomes indefinite to give rise to so-called feathering, with the result that fine lines and fine complicated letters collapse to become indistinct and not readable.
Further, the papers mentioned above are typically subjected to the treatment called "sizing" so that less feathering occurs when writing is manually performed with a writing implement particularly a fountain pen. Therefore, printer ink jet printer, ink does not easily penetrate into the paper and has a poor setting characteristic at the printed portion, whereby scratching of the print may occur by scraping of printed letters against the cover of a printer and ink may stain when the printed matter is smeared by a hand.
Accordingly, various improvements have been made in order to improve setting characteristic of printed letters. For example, there have been attempted the method in which pH is made strongly alkaline, the method in which a large amount of a surfactant is added into an ink or the method in which a water-soluble polymer is added in an ink, etc. The method of making an ink strongly alkaline is dangerous when the ink contacts skin and also involves the problem that both feathering and setting characteristic are not satisfactory for paper treated with a certain kind of sizing agent. On the other hand, the method in which a large amount of a surfactant is added may have the drawback that feathering occurs depending on the kind of paper, that the ink may retract from the orifice surface wets the entire orifice surface and not eject, etc. Further, the method in which a water-soluble polymer is added in the ink, even though some effects can be obtained with respect to feathering and setting characteristic of printed letters, the ink tends to crust at the orifice of the print head, whereby there has been the problem that normal ejection can not be effected when the printer is left to stand unoperated for several minutes.
Although various improvements other than those as described above have been attempted, there has been known no ink which can solve all the problems of feathering, setting characteristic of printed letters, crusting resistance at the print head, etc., as mentioned above.